It's a little more complicated but in rough terms 50% ahead of the hinge point is the critical point. At that point, it will take no effort to turn the wheel as the turning force in front and the force behind will cancel out. This has a couple of bad results:
- You can't feel the forces on the rudder at all so it's not always clear what position it is in. This makes it hard to sail a straight line as there is no tactile feel.
- In the event of a failure, the rudder will wind up in a random position, so you may be stuck sailing in circles.

It's actually about 25% from the leading edge to shaft where the forces are equal, more or less depending of the foil shape, speed and angle of attack. This is due the lift of the rudder which is most close to the leading edge..

big wheels and a few turns lock to lock make for less twitchy helming and so looking away for a second doesn't cause you to veer off course too greatly, but more than a few seconds and you'll probably have turned 90 degrees.

Must say I have come to like the big wheel on my boat. It gives fingertip control from many different positions in the cockpit. It has enough intertia to be spun lock to lock very quickly. It obstructs the cockpit a bit, but everthing is a compromise.

As has been a bit heated to death the reason for a big wheel is leverage. The larger the wheel, the more of it you have without needing to introduce more friction into the system. But there is a bit of an upper limit, at some point the wheel size just gets stupid.

A larger wheel also allows the driver more options of where to sit, generally allowing him to sit as far outboard as possible for the best view of the sails. Smaller wheel restrict this ability. But still super large wheels get stupid on very wide modern boats.

So people started to move to twin wheels. This allows the best size of wheel to be selected, while also allowing the driver to sit as far outboard as possible. They ar not just a silly cosmetic option, there is real purpose to having split wheel systems.

Finally on rudder design... A balanced spade ideally has the rudder post 17% aft of the trailing edge on a vertical rudder. The reasons you guys gave are correct, but the placement was a little off.

__________________
Greg

- If animals weren't meant to be eaten then they wouldn't be made of food.

In modern sailboats the force is usually not that great. I can steer my boat with one finger. If not for the good looks, the key reason nowadays must be to allow the helmsman to sit on either side (for better visibility around, and to the sails, and for better weight balance). Same reasons behind having two steering wheels.

You will find large steering wheels on racing sailing boats
Cruisers have hydraulic steering so there is no need for large steering wheel
Reason that racing boats avoid hydraulics and go for large steering wheel is usually the weight
A hydraulic steering for a 45 racing footer it is tooooo heavy and racing boats need to be light weight
My ex racing boat the once "UNIBANK II" a 45 one off had such a large steering wheel and it was a piece of cake to steer her even in the worst weather condition
She had also a tiny engine , only 27 HP, again to save weight

So I got this response in my thread "cat question" And while it is fairly insulting to me, I also thought it was a very funny post.
So, I thought I would start a thread series asking my curious idiot questions, since I have about a ton of em.
So heres the first one.
Why is the wheel on a sailboat so big?

Now, in case you're thinking this is some kind of joke, it isn't. I really don't know, and am wondering why.

i upsized to the largest wheel that would fit on my boat for one reason. i sit as far to one side or other as possible when steering. driving from the center of a sailboat has never made sense to me. that's while tiller's have hiking sticks. single handing most of the time i can see so much more as regards sail trim, wave action, heel angle, etc., from the rail than i can from the center of the boat. and weight on the high side in a blow is crucial while crew on the low side in light air will heel the boat increasing water line length and helps with sail shape.

50% back for pivot location is much too far back. Even the often suggested 25% back makes for a twitchy steering at speed. I have built a half dozen rudders and found 10% to 15% back makes for a well behaved rudder. Which means it has some feel but doesn't require excessive force

Usually its easier to helm a boat from the windward side. Big wheel allows you to steer from whatever side is convenient for you. Also, its way easier to steer a wheel when you standing at its side then directly in back of it. Directly in back steering tends to mean over/under steering since folks treat it like a car steering wheel(its not)
Steering from the side forces you to steer according to the boat's natural drift off course. You steer ahead of the boat's movement, not afterwards. Its way easier to get into this rhythm when you are abreast of the wheel, not behind it.

Airplanes have balanced rudders as well, here is a photo of my plane, notice the top of the rudder is balanced so that airflow over the top portion counteracts the force of the wind over the rest of the rudder when the rudder is turned.

(hopefully these photos will appear in the proper order)

Now, here is a photo of my boat’s rudder, no balance at all, but it handles easily with a 3’ wheel at 1.5 turns lock to lock. Contrary to what a few have said, the “feel” of the boat through the wheel is important, has the boat heels one feels a bit more pressure, if the boat is balanced the pressure is slight, but if you have no pressure the boat will ten to wander, this happens often with hydraulic steering.

I have built several yachts and did a lot of work on the proper size wheel to the rudder. Here is an 80’ Frers design I built at Palmer Johnson, and subsequently sailed her around the world. She had a 7 foot wheel on a balanced rudder, not quite 1 turn lock to lock. The diameter was this large so one could sit on either side and steer. She sailed like a dream (German Frers is a wizard), and when she would surf at 14 knots (took a BIG sea to surf her), you could steer her with two fingers.

And here is one more boat I built up in Maine at Hodgdon. BIG rudder. She has hydraulic steering with two large wheels, we tried to get feedback with hydraulic gear, but she never really had any feel in either wheel.

TrentePieds is fin keeled and has a spade rudder, regrettably. The rudder stock is set too far back at about 30% cord. 18% cord is good bei mir. My wheel wrecks the back porch for living space, and the house is high enuff to require standing up to see over it. Or leaning out quite far. I'm gonna have a go at a tiller with a hiking stick :-)!

You will find large steering wheels on racing sailing boats
Cruisers have hydraulic steering so there is no need for large steering wheel
Reason that racing boats avoid hydraulics and go for large steering wheel is usually the weight
A hydraulic steering for a 45 racing footer it is tooooo heavy and racing boats need to be light weight
My ex racing boat the once "UNIBANK II" a 45 one off had such a large steering wheel and it was a piece of cake to steer her even in the worst weather condition
She had also a tiny engine , only 27 HP, again to save weight

The reason race boats don't have hydrolic steering is not because of weight, but because of feel. A hydrolic system dampens the feeling of what's going on with the rudder, which is why you don't want a perfectly balanced spade. A slight imbalance allows the helmsman to feel how the rudder is responding but this is only achievable with direct drive.

I actually don't know many small sailboats (<100') built in the last 25 years that use hydrolic steering at all. With modern balanced rudders there really isn't a need to do so. Balanced spade rudders can be designed to a given helm load pretty easily, so why go thru the complexity of a hydrolic system where you don't need one.

The only exception maybe for full keel or unbalanced skeg rudders that can't use better design to reduce the loads.

__________________
Greg

- If animals weren't meant to be eaten then they wouldn't be made of food.

On modern boats a lot of it is for looks (ie; wow mister, you sure do have a big...).

There's definitely some of that at times. When we bought our 35' boat it was fitted with a 36" diameter wheel; you had to walk across the cockpit seating to get around it! We immediately changed that for a 30" wheel and a year or so later, we fitted a 24" wheel - much better for circulation - though we kept the 30" one 'just in case we ever need a bigger wheel, heavy weather and such.' It's never gone back on since and I have never felt short of leverage, nor do I recall there being any significant/noticeable loss of leverage at either reduction in diameter; perhaps if I'd gone directly from 36" to 24" things may have been different? Gearing is just short of one turn either way from centred to full rudder and in most of our heavy-weather steering experiences, the windvane's done the steering; it connects to a hub of only 6-7" diameter, irrespective of what sized wheel it's clamped to.